1. Field of the Invention
The present invention relates to an internal wiring and piping system of a robot for industrial use providing the linear motion mechanism and turning motion mechanism.
2. Description of the Prior Art
In relation to the internal wiring and piping system of the robot for industrial use having a vertical axis, turning axis and expansion axis, the prior art has employed the system explained hereunder.
FIG. 4 and FIG. 5 are illustrations for explaining the structure of the prior art.
In FIG. 4, the reference numeral 1 designates an R axis base plate; an R axis housing 2 is fixed to the R axis base plate 1; rollers 3 are rotatably provided at the positions forming the angle of 120 degrees at the both sides of front and rear sides of R axis housing 2. Two sets of three rollers 3 are respectively provided at the front and rear sections of housing 2. The reference numeral 4 designates extensible R axis pipe provided as the expansion axis supported by six rollers 3; rack 5 is fixed to the R axis pipe 4; rotation stopper block 6 which has two pieces of rotatable rollers, not illustrated, is supporting the right and left sides of rack 5, at the lower section thereof and is fixed to the R axis housing 2; R axis motor plate 7 is fixed to the R axis housing 2; R axis motor 8 is fixed to the R axis motor plate 7; small gear 9 is fixed to the output axis of R axis motor 8; large gear 10 is engaging with small gear 9, rotation of this large gear moves the R axis pipe 4 in its axial direction through rotation of the pinion provided in the R axis housing 2 and engaged with the rack 5; moving end clamp angle 17 is fixed to the R axis pipe 4; belt-shaped thin plate 12 is fixed to the moving end clamp angle 17 and bending lower side of base plate 1 for the R axis pipe 4; cutout part 13 is provided for binding the wirings and pipings along the thin plate 12 with a string type member at several points; and fixing end clamp angle 18 is provided for fixing the fixing end of thin plate 12.
The R axis operates as follows. When the R axis motor 8 revolves, the small gear 9 fixed to the output axis of motor rotates, causing the large gear 10 engaging therewith and pinion gear to rotate. Moreover the rack 5 engaging therewith and the R axis pipe 4 make the extending operation. Thereby, the moving end of the thin plate 12 fixed to the R axis pipe 4 through the moving end clamp angle 17 is also caused to make the extending operation. In this case, since the belt shaped thin plate 12 is bent in the vertical directions, it can be seen from the upper side, that the thin plate 12 lies on the center line of R axis pipe 4 in such entire range from the moving end to the fixing end. Meanwhile, the curvature of thin plate 12 supporting wirings and pipings must be set sufficiently large considering the life expectancy of such wirings and pipings, but the distance in the vertical direction between the moving end and fixing end becomes longer in the vertical direction as much as such consideration. Therefore, the R axis pipe 4, of which the moving end is fixed through the moving end clamp angle 17, is located higher for the base plate 1, of which the fixing end is fixed through the fixing end clamp angle 18, degrading the accuracy.
FIG. 5 illustrates a structure of the turning axis of the prior art. In this figure, 51 designates the T axis frame; T axis motor plate 52 is fixed to the T axis frame 51; T axis motor 53 is fixed to the T axis motor plate 52; small pulley 54 is fixed to the output axis of the T axis motor 53; large pulley 55, having a rotatable worm gear not illustrated within the T axis frame 51, is engaged with small pulley 54 through a belt; T axis bracket 56 is fixed to a rotatable wheel gear, not illustrated, engaging with the worm gear and provided within the T axis frame 51; T axis dog 57 which is fixed to the T axis bracket 56, transmits rotation of the T axis to base plate 1 and guides the vertical motion of base plate 1; upper cutout section 58 is provided for keeping free the R axis pipe 4 making the linear motion and the belt shaped thin plate 12 bending in the vertical direction; and two pieces of rotatable rollers 59 which are fixed to the R axis base plate 1, transmit a driving force of the turning axis to the expansion axis from the T axis dog 57. The T axis may be operated as follows. First, when the T axis motor 53 revolves, the small pulley 54 fixed to the output axis of this motor rotates, causing the large pulley 55 and worm gear engaging therewith through the belt to rotate, followed by the turning operation of the wheel gear, T axis bracket 56 and T axis dog 57 being engaged with such pulley and worm gear. Thereby, the entire part of the R axis including the R axis base plate 1 is also caused to make a turning operation through two pieces of roller 59 fixed to the R axis base plate 1. On the other hand, the R axis as a whole is caused also to make a vertical motion with the vertical axis (hereinafter referred to as the Z axis) 60 which is in the vertical motion by a driving mechanism not illustrated. Accordingly, the R axis base plate 1 makes the vertical motion. However, since the T axis as a whole including the T axis dog does not make the vertical motion, a driving force of the turning axis transmitted from the T axis dog 57 is sent to the expansion axis by the two pieces of rotatable rollers 59 fixed to the R axis base plate 1. In addition, the T axis bracket 56 is closest to the R axis base plate 1 at the position where the Z axis becomes lowest. In this timing, the T axis dog 57 enters the R axis at the relatively deepest position and the cutout section 58 is provided at the upper part in order to avoid collision with the R axis pipe 4. In the method of the prior art, the belt shaped thin plate 12 is bent in the vertical direction and the fixing end is in such a height of the R axis base plate 1 just under the R axis pipe 4. Therefore, the vertical size of upper cutout section 58 becomes long. Therefore, when the base plate 1 is located at the upper end of T axis dog 57, the strength of two pole sections of the T axis dog becomes weak in the turning direction.
As described, the apparatus of the prior art has the following pair of problems resulting from the positional relationship of the moving end and fixing end of the thin plate 12. First, the strength of the drive mechanism is insufficient. Namely, in the shape of mechanism part for transmitting a driving force of the turning axis to the expansion axis, the cutout part provided for making free the pipe which makes linear motion and the belt shaped thin plate bending in the form of a letter U in the vertical direction becomes long also in the vertical direction and thereby when the driving force of the turning axis is to be transmitted to the expansion axis with the upper end, namely the vertical axis is located at the upper end, the strength becomes insufficient. It becomes more apparent when the speed of the turning axis becomes higher, the stroke of the vertical axis becomes longer or the weight to be carried becomes heavier. Second, the height of the robot becomes high. Namely, since the curvature of thin plate supporting wirings and pipings must be large considering the life expectancy of such wiring and pipings, the vertical distance between the moving end and fixing end becomes much longer. Therefore, the fixed pipe of the moving end becomes higher than the base plate fixed at the fixing end through the angle, resulting in degradation of accuracy. It becomes more apparent when the size of the robot becomes smaller. Moveover, the strength of the drive mechanism becomes more insufficient as much as considering life expectancy.